#ifndef ACTIVATIONS_H
#define ACTIVATIONS_H
#include "cuda.h"
#include "math.h"

/*
**  所有的激活函数类别（枚举类）
*/
typedef enum{
    LOGISTIC, RELU, RELIE, LINEAR, RAMP, TANH, PLSE, LEAKY, ELU, LOGGY, STAIR, HARDTAN, LHTAN
}ACTIVATION;

ACTIVATION get_activation(char *s);

char *get_activation_string(ACTIVATION a);
float activate(float x, ACTIVATION a);
float gradient(float x, ACTIVATION a);
void gradient_array(const float *x, const int n, const ACTIVATION a, float *delta);
void activate_array(float *x, const int n, const ACTIVATION a);
#ifdef GPU
void activate_array_ongpu(float *x, int n, ACTIVATION a);
void gradient_array_ongpu(float *x, int n, ACTIVATION a, float *delta);
#endif

static inline float stair_activate(float x)
{
    int n = floor(x);
    if (n%2 == 0) return floor(x/2.);
    else return (x - n) + floor(x/2.);
}
static inline float hardtan_activate(float x)
{
    if (x < -1) return -1;
    if (x > 1) return 1;
    return x;
}
static inline float linear_activate(float x){return x;}
static inline float logistic_activate(float x){return 1./(1. + exp(-x));}
static inline float loggy_activate(float x){return 2./(1. + exp(-x)) - 1;}
static inline float relu_activate(float x){return x*(x>0);}
static inline float elu_activate(float x){return (x >= 0)*x + (x < 0)*(exp(x)-1);}
static inline float relie_activate(float x){return (x>0) ? x : .01*x;}
static inline float ramp_activate(float x){return x*(x>0)+.1*x;}
static inline float leaky_activate(float x){return (x>0) ? x : .1*x;}
static inline float tanh_activate(float x){return (exp(2*x)-1)/(exp(2*x)+1);}
static inline float plse_activate(float x)
{
    if(x < -4) return .01 * (x + 4);
    if(x > 4)  return .01 * (x - 4) + 1;
    return .125*x + .5;
}

static inline float lhtan_activate(float x)
{
    if(x < 0) return .001*x;
    if(x > 1) return .001*(x-1) + 1;
    return x;
}
static inline float lhtan_gradient(float x)
{
    if(x > 0 && x < 1) return 1;
    return .001;
}

static inline float hardtan_gradient(float x)
{
    if (x > -1 && x < 1) return 1;
    return 0;
}

// 返回线性激活函数（就是f(x)=x）关于输入x的导数值
static inline float linear_gradient(float x){return 1;}

// 返回logistic (sigmoid) function关于输入x的导数值
static inline float logistic_gradient(float x){return (1-x)*x;}

static inline float loggy_gradient(float x)
{
    float y = (x+1.)/2.;
    return 2*(1-y)*y;
}
static inline float stair_gradient(float x)
{
    if (floor(x) == x) return 0;
    return 1;
}

// 返回线性矫正单元（ReLU）非线性激活函数关于输入x的导数
static inline float relu_gradient(float x){return (x>0);}

// 返回指数线性单元（Exponential Linear Unit, ELU）非线性激活函数关于输入x的导数值
static inline float elu_gradient(float x){return (x >= 0) + (x < 0)*(x + 1);}

static inline float relie_gradient(float x){return (x>0) ? 1 : .01;}

static inline float ramp_gradient(float x){return (x>0)+.1;}

// 返回leaky ReLU非线性激活函数关于输入x的导数值
static inline float leaky_gradient(float x){return (x>0) ? 1 : .1;}

// 返回tanh非线性激活函数关于输入x的导数值
static inline float tanh_gradient(float x){return 1-x*x;}

static inline float plse_gradient(float x){return (x < 0 || x > 1) ? .01 : .125;}

#endif

